Relay centric mobility management in a mesh network

Abstract

Systems and methods are disclosed for efficient signaling between devices. A relay device initiates association with discovery broadcast signals to leaf devices. Each leaf responds with association request signals. After association, the relay periodically sends stay alive signals to the leaf, and the leaf periodically sends link confirmation signals to the relay. If either device fails to send its signal, link breakage is assumed. The leaf device reverts to uplink communication with a base station while searching for another relay. In another embodiment, the leaf foregoes association with a relay, instead forming a device to device (D2D) connection with a relay. A D2D connection is used when the leaf does not expect a link to a relay to be stable enough to justify the association overhead, or when downlink traffic is arriving more frequently than an associated relay is awake. Other aspects, embodiments, and features are also claimed and described.

What is claimed is: 
     
       1. A method comprising:
 associating, by a first wireless communications device, with a relay wireless communications device during a first awake period common to the first wireless communications device and the relay wireless communications device; 
 monitoring, by the first wireless communications device during a second awake period, for a stay alive signal from the relay wireless communications device transmitted at a first periodic rate regardless of whether there is traffic to receive; and 
 sending, by the first wireless communications device during a third awake period, a link confirmation signal to the relay wireless communications device at a second periodic rate regardless of whether there is traffic to transmit, 
 wherein the first periodic rate and the second periodic rate are different, and 
 wherein the first wireless communications device is asleep at a time that overlaps a sleep time of the relay wireless communications device. 
 
     
     
       2. The method of  claim 1 , further comprising:
 maintaining, by the first wireless communications device, a list of one or more second wireless communications devices, the one or more second wireless communications devices identified from one or more discovery broadcast signals; and 
 selecting, by the first wireless communications device, the relay wireless communications device from the list of one or more second wireless communication devices during the first awake period. 
 
     
     
       3. The method of  claim 2 , wherein the selecting the relay wireless communications device is based on one or more parameters including:
 an amount of energy consumption used to transmit to a third wireless communications device via the relay wireless communications device, 
 a number of intermediate relays to the third wireless communications device, or 
 whether awake periods of the relay wireless communications device overlap with awake periods of the first wireless communications device. 
 
     
     
       4. The method of  claim 2 , further comprising:
 receiving the one or more discovery broadcast signals at a third periodic rate; and 
 moving, by the first wireless communications device, out of range of the relay wireless communications device at a fourth periodic rate. 
 
     
     
       5. The method of  claim 1 , wherein associating further comprises:
 sending, from the first wireless communications device to the relay wireless communications device, an association request signal including an expected upload traffic periodicity. 
 
     
     
       6. The method of  claim 1 , further comprising:
 determining, at the first wireless communications device, a link breakage to the relay wireless communications device in response to failing to receive an expected stay alive signal from the relay wireless communications device; 
 selecting, by the first wireless communications device, a target relay wireless communications device from one or more second wireless communications devices; and 
 associating, by the first wireless communications device, with the target relay wireless communications device. 
 
     
     
       7. The method of  claim 6 , further comprising:
 communicating, by the first wireless communications device, with a third wireless communications device via the target relay wireless communications device; 
 receiving, at the first wireless communications device from at least one of the one or more second wireless communications devices, one or more corresponding discovery broadcast signals; and 
 sending, by the first wireless communications device to the third wireless communications device, an uplink signal during the association with the target relay wireless communications device, 
 wherein the sending the uplink signal is independent from the target wireless communications device, and 
 wherein the selecting is based on one or more parameters including an amount of energy consumption used to transmit to the third wireless communications device via the target relay wireless communications device, a number of intermediate relays to the third wireless communications device, and whether awake periods of the target relay wireless communications device overlap with awake periods of the first wireless communications device, and 
 the parameters are determined by the first wireless communications device from information included in the one or more discovery broadcast signals. 
 
     
     
       8. The method of  claim 1 , further comprising:
 receiving, at the first wireless communications device from a third wireless communications device via the relay wireless communications device, a downlink page signal; and 
 sending, from the first wireless communications device to the third wireless communications device via the relay wireless communications device, a connection request signal for the third wireless communications device in response to the downlink page signal. 
 
     
     
       9. The method of  claim 1 , further comprising:
 receiving, at the first wireless communications device from a third wireless communications device, a downlink page signal; 
 sending, from the first wireless communications device to a non-associated relay wireless communications device, a device to device connection request; 
 receiving, at the first wireless communications device from the non-associated relay wireless communications device, a device to device connection setup signal; and 
 sending, from the first wireless communications device to the third wireless communications device via the non-associated relay wireless communications device, a connection request signal for the third wireless communications device. 
 
     
     
       10. A method comprising:
 sending, from a first wireless communications device to a second wireless communications device, a discovery broadcast signal during a first awake period that occurs at a first periodic rate; 
 receiving, from the second wireless communications device, an association request signal during a second awake period; 
 sending, from the first wireless communications device to the second wireless communications device during a third awake period, a stay alive signal at a second periodic rate; and 
 monitoring, by the first wireless communications device during a fourth awake period, for a link confirmation signal from the second wireless communications device transmitted at a third periodic rate that is different from the second periodic rate. 
 
     
     
       11. The method of  claim 10 , wherein the discovery broadcast signal includes information used for by the second wireless communications device to determine one or more parameters including:
 an amount of energy consumption necessary for the second wireless communications device to transmit to a third wireless communications device via the first wireless communications device, 
 a number of intermediate relays to the third wireless communications device from the second wireless communications device, and 
 whether awake periods of the first wireless communications device overlap with awake periods of the second wireless communications device. 
 
     
     
       12. The method of  claim 10 , further comprising:
 determining, at the first wireless communications device, a link breakage to the second wireless communications device in response to failing to receive an expected link confirmation signal from the second wireless communications device. 
 
     
     
       13. The method of  claim 10 , further comprising:
 receiving, at the first wireless communications device from the second wireless communications device, a connection request for a third wireless communications device; 
 relaying, from the first wireless communications device to the third wireless communications device, the connection request; 
 receiving, at the first wireless communications device from the second wireless communications device, a connection setup complete signal and a service request for the third wireless communications device; and 
 relaying, from the first wireless communications device to the third wireless communications device, the connection setup complete signal and the service request. 
 
     
     
       14. The method of  claim 13 , further comprising:
 receiving, at the first wireless communications device from the third wireless communications device, a downlink page for the second wireless communications device; and 
 relaying, from the first wireless communications device to the second wireless communications device, the downlink page. 
 
     
     
       15. The method of  claim 10 , further comprising:
 receiving, at the first wireless communications device from a non-associated second wireless communications device, a device to device connection request; 
 sending, from the first wireless communications device to the non-associated second wireless communications device, a device to device connection setup signal; 
 receiving, at the first wireless communications device from the non-associated second wireless communications device, a connection request for a third wireless communications device; and 
 relaying, from the first wireless communications device to the third wireless communications device, the connection request. 
 
     
     
       16. The method of  claim 15 , further comprising:
 receiving, at the first wireless communications device from the third wireless communications device, a connection setup signal for the non-associated second wireless communications device; and 
 relaying, from the first wireless communications device to the non-associated second wireless communications device, the connection setup signal. 
 
     
     
       17. The method of  claim 15 , further comprising:
 receiving, at the first wireless communications device from the non-associated second wireless communications device, a connection setup complete signal and a service request for the third wireless communications device; and 
 relaying, from the first wireless communications device to the third wireless communications device, the connection setup complete signal and the service request. 
 
     
     
       18. The method of  claim 10 , wherein the first awake period is the same as the second awake period. 
     
     
       19. An apparatus, comprising:
 a processor configured to generate a link confirmation signal; and 
 a transceiver configured to:
 establish association with a relay wireless communications device during a first awake period common to the apparatus and the relay wireless communications device; 
 monitor, during a second awake period, for a stay alive signal from the relay wireless communications device transmitted at a first periodic rate regardless of whether there is traffic to receive; and 
 send, during a third awake period, the link confirmation signal to the relay wireless communications device at a second periodic rate regardless of whether there is traffic to transmit, wherein the first periodic rate and the second periodic rate are different. 
 
 
     
     
       20. The apparatus of  claim 19 , wherein:
 the transceiver is further configured to receive one or more discovery broadcast signals from one or more second wireless communications devices; and 
 the processor is further configured to:
 maintain a list of the one or more second wireless communications devices, the one or more second wireless communications devices identified from the one or more discovery broadcast signals; and 
 select the relay wireless communications device from the list of the one or more second wireless communications devices during the first awake period. 
 
 
     
     
       21. The apparatus of  claim 20 , wherein the processor is further configured to:
 populate the list of the one or more second wireless communications devices based on one or more corresponding discovery broadcast signals. 
 
     
     
       22. The apparatus of  claim 19 , wherein:
 the processor is further configured to generate an association request signal; and 
 the transceiver is further configured to send, to the relay wireless communications device, the association request signal including an expected upload traffic periodicity. 
 
     
     
       23. The apparatus of  claim 19 , wherein the processor is further configured to:
 determine a link breakage to the relay wireless communications device in response to the transceiver failing to receive an expected stay alive signal from the relay wireless communications device. 
 
     
     
       24. The apparatus of  claim 23 , wherein the processor is further configured to:
 select a target relay wireless communications device from one or more second wireless communications devices; and 
 initiate association with the target relay wireless communications device. 
 
     
     
       25. An apparatus comprising:
 a processor configured to generate a discovery broadcast signal; and 
 a transceiver configured to:
 send, to a second wireless communications device, the discovery broadcast signal during a first awake period that occurs at a first periodic rate; 
 receive, from the second wireless communications device, an association request signal during a second awake period; 
 send, to the second wireless communications device during a third awake period, a stay alive signal at a second periodic rate; and 
 monitor, during a fourth awake period, for a link confirmation signal from the second wireless communications device transmitted at a third periodic rate that is different from the second periodic rate. 
 
 
     
     
       26. The apparatus of  claim 25 , wherein the discovery broadcast signal includes information used for by the second wireless communications device to determine one or more parameters including:
 an amount of energy consumption necessary for the second wireless communications device to transmit to a third wireless communications device via the apparatus, 
 a number of intermediate relays to the third wireless communications device from the second wireless communications device, and 
 whether awake periods of the apparatus overlap with awake periods of the second wireless communications device. 
 
     
     
       27. The apparatus of  claim 25 , wherein the processor is further configured to:
 determine a link breakage to the second wireless communications device in response to failing to receive an expected link confirmation signal from the second wireless communications device. 
 
     
     
       28. The apparatus of  claim 25 , wherein the transceiver is further configured to:
 send, to a third wireless communications device, an associated device update signal. 
 
     
     
       29. The apparatus of  claim 25 , wherein the transceiver is further configured to:
 receive, from the second wireless communications device, a connection request for a third wireless communications device; 
 relay, to the third wireless communications device, the connection request; 
 receive, from the second wireless communications device, a connection setup complete signal and a service request for the third wireless communications device; and 
 relay, to the third wireless communications device, the connection setup complete signal and the service request. 
 
     
     
       30. The apparatus of  claim 25 , wherein the transceiver is further configured to:
 receive, from a non-associated second wireless communications device, a device to device connection request; 
 send, to the non-associated second wireless communications device, a device to device connection setup signal; 
 receive, from the non-associated second wireless communications device, a connection request for a third wireless communications device; and 
 relay, to the third wireless communications device, the connection request.